Sebastian Faulks said that by focusing on single molecules of human existence, he tried to reveal wider truths about humanity. Photograph: Tracey Croggon/Royal Society

An idea, like a story, can be big or little. It can tackle the heart of human nature, or the nature of a single human heart.

This weekend at the Royal Society, the One Culture festival explored the sweeping narratives and the smaller dramas of science and literature, of individual scientists and their great ideas. Science's most elite club opened its doors to writers like Sebastian Faulks, Michael Frayn, John Banville; dancers from the Rambert Dance Company; Take the Space theatre company; and scientists who manage to combine artistic pursuits with a research career.

The title "One Culture" is a play on the famous C P Snow speech, in which he described the way that science and the humanities had separated into two separate cultures.

For Sir Paul Nurse, president of the Royal Society, the festival was not about the difference between science and art, but about "somehow coming to a better understanding, about the world and ourselves".

In his conversation with Uta Frith on Sunday, Sebastian Faulks described how he starts with a big idea, then narrows his focus to a story that can illustrate it, and the characters who can make that possible: much like a scientist, who starts with a question about how the world works and narrows the focus of their microscope to the tiny part of it that can answer that question. Through focusing on single molecules of human existence, Faulks reveals the wider truths about humanity.

He spoke particularly about Stephen, the central character in his book Birdsong. With his calm, cold detachment from the world, Stephen was the only character who could allow Faulks to explore the depths to which humanity can sink.

But it is not enough merely to observe your characters – a writer must manipulate what happens in their fiction. In her talk on Sunday, Sunetra Guptra, a scientist, novelist and essayist, described her fiction as "an experiment". In both science and fiction, the basis of this experiment is to find something from the world, be it a set of particles, cells or characters, that can help you to answer a question. You expose it to certain conditions, and learn from how it responds.

This approach resonated with how Faulks worked with his characters and how he puts himself into a character, so that he can "report back". What he finds once he is there, he said, can sometimes surprise him. He talked about how although he can govern his characters' general movements, their responses to individual moments can come as a surprise. To him, the essence of any narrative is a character doing something wholly unexpected and uncharacteristic.

In science, too, it is when something behaves in a way you would not expect that the excitement begins. Ernest Rutherford, for instance, spent years firing charged particles at a fine sheet of gold foil. Time and again they went straight through, but only when one acted completely out of character, and bounced back, did he hypothesise the nuclear model of the atom which we still use today.

There are countless other stories like this from science, and the finer and more precise our tools of observation become, the more surprises we uncover about the world and ourselves. The novel Faulks is currently writing relies upon the scientific breakthrough – well into the future – of being able to observe the actions of single brain cells. In this future world, scientists identify the link between our memory and sense of self. From a tiny neuron, we encounter a big idea.

The process is circular. For the Rambert Dance Company, and their scientist in residence Nicky Clayton, the big ideas of science have informed some of their most challenging dances. For them, the boundaries of "science" and "art" are artificial – what links them is far more basic. As Mark Baldwin, director of Rambert, put it:

"The commonalities at the base of it all are enormous. We're talking about ideas."

The ideas they both get excited about are big, abstract ones. Clayton, as scientist in residence at Rambert, talks to the dancers about scientific ideas. She has to think carefully about what can be put into movement. For her, these movements are not just a way of communicating, or illustrating these ideas. They are about inspiration. And this inspiration has found its way back into her science, as shown by this video from Cambridge University (note the opening Stephen Fry voiceover!)

The central premise of One Culture was that science and the arts are not separate entities, but parts of the same whole of human culture. While George Eliot used a "tiny drop of ink" for her mirror onto the world, Rutherford used tiny gold particles. They, together with all artists and scientists, are trying to understand the world. And the weekend showed that the commonalities between the artistic and scientific approach far outweigh the differences.

Half a century after Snow spoke about the gulf between the arts and humanities, it is high time that two cultures became one.